This study has been done to determine the galvanic interaction between five types of grinding media (mild steel, cast iron, 10% chromium, 20% chromium, and ceramic media) and galena, in situ of the mill. The ceramic media has a... more
This study has been done to determine the galvanic interaction between five types of grinding media (mild steel, cast iron, 10% chromium, 20% chromium, and ceramic media) and galena, in situ of the mill. The ceramic media has a significantly not galvanic interaction with galena and high chromium media has a significantly weaker galvanic interaction with galena, and produces a very much lower amount of oxidize iron species in the mill discharge than mild steel medium. The investigation of the various reactions occurring on the galena surface was investigated by ethylene diamine-tetra acetic acid disodium salt (EDTA) extraction and X-ray photoelectron spectroscopy (XPS) measurements. The floatability of galena is dependent on the galvanic current between grinding media and galena during grinding because the current is relative to the amount of iron oxidation species and the reduction rate on galena. Iron oxidation species depressed galena flotation. The optimum galena flotation was achieved by selecting grinding conditions that enabled iron oxidation to be controlled.
In this paper, prediction of copper and molybdenum grades and their recoveries of an industrial flotation plant are investigated using the Artificial Neural Networks (ANN) model. Process modeling has done based on 92 datasets collected at... more
In this paper, prediction of copper and molybdenum grades and their recoveries of an industrial flotation plant are investigated using the Artificial Neural Networks (ANN) model. Process modeling has done based on 92 datasets collected at different operational conditions and feed characteristics. The prominent parameters investigated in this network were pH, collector, frother and FOil concentration, size percentage of feed passing 75 microns, moisture content in feed, solid percentage, and grade of copper, molybdenum, and iron in feed. A multilayer perceptron neural network, with 10:10:10:4 structure (two hidden layers), was used to estimate metallurgical performance. To obtain the optimal hidden layers and nodes in a layer, a trial and error procedure was done. In training and testing phases, it achieved quite correlations of 0.98 and 0.93 for Copper grade, of 0.99 and 0.92 for Copper recovery, of 0.99 and 0.92 for Molybdenum grade and of 0.99 and 0.94 for Molybdenum recovery prediction, respectively. The proposed neural network model can be applied to determine the most beneficial operational conditions for the expected Copper and Molybdenum grades and their recovery in final concentration of the industrial copper flotation process.
Results of the experimental measurements on the partial molar volume of kerosene used as a medium for dissolving TBP are utilized to determine the activity of TBP in the binary kerosene-TBP solution through the application of Gibbs-Duhem... more
Results of the experimental measurements on the partial molar volume of kerosene used as a medium for dissolving TBP are utilized to determine the activity of TBP in the binary kerosene-TBP solution through the application of Gibbs-Duhem equation. The treatment is based on combination of the experimental data with the thermodynamic values available on the compressibility factor of pure kerosene at room temperature. It is shown that the activity of TBP in kerosene has a positive deviation from ideality with an activity coefficient derived as follows: 1
The extraction of chromium(III) from a model waste solution and also from a waste solution of an Indian tannery with Amberlite IR 120 resin is described, and the performance of this resin is compared with other similar resins. The... more
The extraction of chromium(III) from a model waste solution and also from a waste solution of an Indian tannery with Amberlite IR 120 resin is described, and the performance of this resin is compared with other similar resins. The parameters that were optimized include effect of mixing time, pH, loading and elution behaviours of chromium(III) for this resin. Sorption of chromium(III) on Amberlite IR 120 followed Freundlich isotherm and Langmuir isotherm model, and the maximum sorption capacity was determined to be 142.86 mg Cr(III)/g of the resin. Higher Freundlich constant (K f ) values (6.30 and 13.46 for aqueous feed of 500 and 1000 ppm Cr(III)) indicated strong chemical interaction through ion exchange mechanism of the metal ion with the resin. The kinetic data showed good fit to the Lagergren first order model for extraction of chromium(III). Desorption of chromium(III) from the loaded resin increased with the increase in concentration of eluent (5-20% H 2 SO 4 ). With 20% (v/v) sulphuric acid solution 94% chromium(III) was eluted in three stages. Elution of the Cr(III) in the column experiments was however, found to be lower (82%) than that of the shake flask data. In case of Indian tannery's waste solution, it was observed that almost total chromium was extracted in four stages with Amberlite IR 120. P. MESHRAM ET AL. 33 Indion 790. Both the resins showed constant chromium(III) extraction in the pH range 1.0 -3.5. Beyond pH 3.5 extraction of chromium(III) with Indion 790 drastically
The sulfuric acid leaching of zinc plant residues was studied in an attempt to find a suitable hydrometallurgical method for zinc recovery. The parameters evaluated consist of reaction time, Solid-to-liquid-ratio, reaction temperature,... more
The sulfuric acid leaching of zinc plant residues was studied in an attempt to find a suitable hydrometallurgical method for zinc recovery. The parameters evaluated consist of reaction time, Solid-to-liquid-ratio, reaction temperature, agita- tion rate and pH. The results of kinetic analysis of the leaching data under various experimental conditions indicated that there is a reaction controlled by the solution transport of protons through the porous product layer with activation energy of about 1 kJ/mol for different constant solid to liquid ratios. Based on the shrinking core model (SCM). On the other hand, activation energy was obtained from a model-free method using isothermal measurements. Values for activation energy were calculated as a result of the conversion function with an average of 2.9 kJ/mol. This value is close to that determined previously, using shrinking core model (SCM).
Polyaniline stannic molybdate-an organic-inorganic composite material, was prepared via sol-gel mixing of organic polymer polyaniline into matrices of inorganic precipitate of stannicmolybdate. The composite material synthesized at pH 1.2... more
Polyaniline stannic molybdate-an organic-inorganic composite material, was prepared via sol-gel mixing of organic polymer polyaniline into matrices of inorganic precipitate of stannicmolybdate. The composite material synthesized at pH 1.2 showed an ion exchange capacity 1.8 meq/g for Na + ions. Ion exchange capacity, pH titration and distribution studies were carried out to determine the preliminary ion exchange properties of the material. The distribution studies showed the selectivity of Hg(II) ions by this material. The effect of temperature on the ion exchange capacity of the material at different temperatures had been studied. The sorption behavior of metal ions was also explored in different surfactant media.
The solution purification process is an essential step in zinc hydrometallurgy. The performance of solution purification directly affects the normal functioning and economical benefits of zinc hydrometallurgy. This paper summarizes the... more
The solution purification process is an essential step in zinc hydrometallurgy. The performance of solution purification directly affects the normal functioning and economical benefits of zinc hydrometallurgy. This paper summarizes the authors' recent work on the modeling, optimization, and control of solution purification process. The online measurable property of the oxidation reduction potential (ORP) and the multiple reactors, multiple running statuses characteristic of the solution purification process are extensively utilized in this research. The absence of reliable online equipment for detecting the impurity ion concentration is circumvented by introducing the oxidation-reduction potential into the kinetic model. A steady-state multiple reactors gradient optimization, unsteady-state operational-pattern adjustment strategy, and a process evaluation strategy based on the oxidation-reduction potential are proposed. The effectiveness of the proposed research is demonstrated by its industrial experiment.
Solvent extraction of base metals using bis((1-decylbenzimidazol-2-yl)methyl)amine (BDNNN) showed a lack of pH-metric separation of the metals. The extraction system was described quantitatively using the equilibria involved to derive the... more
Solvent extraction of base metals using bis((1-decylbenzimidazol-2-yl)methyl)amine (BDNNN) showed a lack of pH-metric separation of the metals. The extraction system was described quantitatively using the equilibria involved to derive the mathematical explanation for the two linear log D vs pH e plots for each metal ion extraction curve, and coordination numbers could also be extracted from the two slopes. The lack of separation was attributed to the absence of stereochemical "tailor making" since the complexes isolated from the reaction of the ligand, bis((1H-benzimidazol-2-yl)methyl)amine (NNN), with base metals suggested the formation of similar octahedral complex species from spectral and crystal structure evidence. The bis tridentate coordination observed was in agreement with information extracted from the extraction data. This investigation opens up an opportunity and an approach for the evaluation of amines as extractants but cautions against tridentate ligands.
Conventional methods for precious metals gravimetric concentration involve equipment such as shaking tables, centrifuging concentrators, jigs, trommels, or a combination of those. A less commonly used technique is elutriation, which... more
Conventional methods for precious metals gravimetric concentration involve equipment such as shaking tables, centrifuging concentrators, jigs, trommels, or a combination of those. A less commonly used technique is elutriation, which represents an efficient, safe and low-cost method of separation. The goal of the present investigation was to make a comparative study of gold concentration by elutriation from different precious metal bearing ores: an oxide ore, a mineral consisting of a sulfide matrix, a mineral in which the precious metals are free and disseminated and a slimy and clayey black sand material. The best recoveries of precious metals by elutriation were attained for the free disseminated ore and for the black sands, obtaining gold recoveries of 70% and 96% respectively, with appreciable ratios of concentration as well.
Ethylenediaminetetraacetic acid (EDTA) is a chelating agent that has been used for decontamination purposes in nuclear industry. The presence of EDTA in decontamination wastes can cause complexation of the cations resulting into... more
Ethylenediaminetetraacetic acid (EDTA) is a chelating agent that has been used for decontamination purposes in nuclear industry. The presence of EDTA in decontamination wastes can cause complexation of the cations resulting into interferences in their removal by various treatment processes such as chemical precipitation, ion exchange etc. Further, it might also impart elevated leachability of cationic contaminants from the conditioned wastes immobilized in cement or other matrices and can negatively influence the quality of the final form of waste. In the present study, kinetics of degradation of EDTA (20,000 mg/l) by employing either Photo-Fenton process using UV (15 W λ max = 253.7 nm) or Sono-Fenton process using ultrasound at 130 KHz or simultaneous Sono-Photo Fenton process has been investigated. EDTA is effectively degraded by the synergistic effect of both Photo Fenton and Sono Fenton process. All the above mentioned processes were found to follow a first order kinetics reaction. From the observed pH changes during the oxidation processes, it can be concluded that there is a loss of chelating ability of EDTA. Formation of amides was confirmed during the degradation processes.
A procedure for evaluating the degree of spheroidization of phosphide platelets in cast Cu-4%Sn-5%P alloys using fractal analysis was investigated. The specimens were obtained by melting copper and tin in an improvised clay mould raised... more
A procedure for evaluating the degree of spheroidization of phosphide platelets in cast Cu-4%Sn-5%P alloys using fractal analysis was investigated. The specimens were obtained by melting copper and tin in an improvised clay mould raised to a temperature of 1850˚C ± 20˚C, holding for a period of 10 minutes to 1 hour to modify the aspect ratio of the phosphide platelets. It was found that these platelets have the tendency to change their shape from being spherical to more Euclidian shapes as time elapses. It was found that the inter-platelets distances are approximately equal with time. This effect was more pronounced in samples with high holding time.
The application of D2EHPA in zinc solvent extraction has extensive background. To utilize more effectively, response surface methodology was used to optimize the concentration condition of zinc pregnant solution (ZPL) extracted by D2EHPA.... more
The application of D2EHPA in zinc solvent extraction has extensive background. To utilize more effectively, response surface methodology was used to optimize the concentration condition of zinc pregnant solution (ZPL) extracted by D2EHPA. In the current research, zinc, iron and manganese extraction along with separation factor of zinc-iron (Sf (Zn-Fe)) and zinc-manganese (Sf (Zn-Mn)) were considered as the response values. The optimal ZPL conditions extracted with 30% D2EHPA as the extraction solvent were as follows: Zn 21.96 g/L, Fe 382.57 ppm, Mn 1 g/L, Sf (Zn-Fe) 8.26 and Sf (Zn-Mn) 1529.82. In addition, it was found that the iron and manganese concentration were the most effective factors affecting the zinc and manganese extraction, respectively.
The extraction of chromium(III) from a model waste solution and also from a waste solution of an Indian tannery with Amberlite IR 120 resin is described, and the performance of this resin is compared with other similar resins. The... more
The extraction of chromium(III) from a model waste solution and also from a waste solution of an Indian tannery with Amberlite IR 120 resin is described, and the performance of this resin is compared with other similar resins. The parameters that were optimized include effect of mixing time, pH, loading and elution behaviours of chromium(III) for this resin. Sorption of chromium(III) on Amberlite IR 120 followed Freundlich isotherm and Langmuir isotherm model, and the maximum sorption capacity was determined to be 142.86 mg Cr(III)/g of the resin. Higher Freundlich constant (K f ) values (6.30 and 13.46 for aqueous feed of 500 and 1000 ppm Cr(III)) indicated strong chemical interaction through ion exchange mechanism of the metal ion with the resin. The kinetic data showed good fit to the Lagergren first order model for extraction of chromium(III). Desorption of chromium(III) from the loaded resin increased with the increase in concentration of eluent (5-20% H 2 SO 4 ). With 20% (v/v) sulphuric acid solution 94% chromium(III) was eluted in three stages. Elution of the Cr(III) in the column experiments was however, found to be lower (82%) than that of the shake flask data. In case of Indian tannery's waste solution, it was observed that almost total chromium was extracted in four stages with Amberlite IR 120. P. MESHRAM ET AL. 33 Indion 790. Both the resins showed constant chromium(III) extraction in the pH range 1.0 -3.5. Beyond pH 3.5 extraction of chromium(III) with Indion 790 drastically
In the present paper, separation of nickel and cobalt in ammonia-ammonium carbonate solution that simulates pregnant leach solution of Caron Process by solvent extraction using LIX 84-ICNS was studied. LIX 84-ICNS is a novel extractant... more
In the present paper, separation of nickel and cobalt in ammonia-ammonium carbonate solution that simulates pregnant leach solution of Caron Process by solvent extraction using LIX 84-ICNS was studied. LIX 84-ICNS is a novel extractant which is still being studied, especially for nickel and cobalt separation in ammonia-ammonium carbonate solution. A series of solvent extraction tests were performed at various equilibrium pH, temperature, extractant concentration, and volume ratio of organic to aqueous solution (O/A ratio). The investigation results show that the highest nickel and cobalt extraction percentages of 99.8% and 90.3% were obtained from the extraction test at equilibrium pH of 8.75, temperature of 55˚C, extractant concentration of 40% (v/v) and O/A ratio of 1/1, respectively. Oxidation of cobalt in aqueous solution prior to extraction is needed to minimize co-extraction of cobalt. Co-extracted cobalt can be decreased from 90.3% to 30.3% by mixing 1% (v/v) H2O2 in aqueous solution prior to the extraction stage. It was found that nickel and cobalt extractions by LIX 84-ICNS are endothermic processes with enthalpy changes of +171.03 and +7.64 kJ/mole, respectively. Based on constructed McCabe-Thiele Diagram, nickel extraction level of more than 99.9% can be obtained in 2 stages at O/A ratio of 0.5. The highest stripping percentages of nickel and cobalt of 98.82% and 3.16%, respectively were obtained at 200 g/l H 2 SO 4 as stripping agent.
The application of D2EHPA in zinc solvent extraction has extensive background. To utilize more effectively, response surface methodology was used to optimize the concentration condition of zinc pregnant solution (ZPL) extracted by D2EHPA.... more
The application of D2EHPA in zinc solvent extraction has extensive background. To utilize more effectively, response surface methodology was used to optimize the concentration condition of zinc pregnant solution (ZPL) extracted by D2EHPA. In the current research, zinc, iron and manganese extraction along with separation factor of zinc-iron (Sf (Zn-Fe)) and zinc-manganese (Sf (Zn-Mn)) were considered as the response values. The optimal ZPL conditions extracted with 30% D2EHPA as the extraction solvent were as follows: Zn 21.96 g/L, Fe 382.57 ppm, Mn 1 g/L, Sf (Zn-Fe) 8.26 and Sf (Zn-Mn) 1529.82. In addition, it was found that the iron and manganese concentration were the most effective factors affecting the zinc and manganese extraction, respectively.
The extraction of Bi(III) in nitrate media has been investigated using aminododecyldimethylenediphosphonic acid, ADDMDPA, which was previously synthesized and characterized. The extraction of the cation was carried out in different media... more
The extraction of Bi(III) in nitrate media has been investigated using aminododecyldimethylenediphosphonic acid, ADDMDPA, which was previously synthesized and characterized. The extraction of the cation was carried out in different media with the addition of CH 3 COONa, KNO 3 and HNO 3. The maximum extraction yield for Bismuth is 70% after addition of 0.01 M of potassium nitrate at pHi = 2.9, in one step.
In the present study, porous structure of raw and calcined phosphate ore particles was examined. The specific surface area and the pore volume were determined by nitrogen adsorption. Raw particles and calcined ores were leached using... more
In the present study, porous structure of raw and calcined phosphate ore particles was examined. The specific surface area and the pore volume were determined by nitrogen adsorption. Raw particles and calcined ores were leached using dilute phosphoric acid solution (4% P 2 O 5). In all cases, the ESEM (Environmental Scanning Electron Microscopy) observations show that the grain of phosphate holds its shape ovoidale. The sample heated at 780˚C presented the lowest specific surface area 0.6 m 2 /g at each reaction time, and the unreacted phases were analysed using XRD, FT-IR, Nitrogen adsorption and ESEM observations. The selective leaching curves were evaluated in order to test the validity of kinetics models. A mathematical model in the following form was applied: (() − − = ln 1 α m kt). The dissolution of the two samples (raw and calcined phosphate) has been observed to take place in two steps: the first being fast and the second being slow.
In the present paper, separation of nickel and cobalt in ammonia-ammonium carbonate solution that simulates pregnant leach solution of Caron Process by solvent extraction using LIX 84-ICNS was studied. LIX 84-ICNS is a novel extractant... more
In the present paper, separation of nickel and cobalt in ammonia-ammonium carbonate solution that simulates pregnant leach solution of Caron Process by solvent extraction using LIX 84-ICNS was studied. LIX 84-ICNS is a novel extractant which is still being studied, especially for nickel and cobalt separation in ammonia-ammonium carbonate solution. A series of solvent extraction tests were performed at various equilibrium pH, temperature, extractant concentration, and volume ratio of organic to aqueous solution (O/A ratio). The investigation results show that the highest nickel and cobalt extraction percentages of 99.8% and 90.3% were obtained from the extraction test at equilibrium pH of 8.75, temperature of 55˚C, extractant concentration of 40% (v/v) and O/A ratio of 1/1, respectively. Oxidation of cobalt in aqueous solution prior to extraction is needed to minimize co-extraction of cobalt. Co-extracted cobalt can be decreased from 90.3% to 30.3% by mixing 1% (v/v) H2O2 in aqueous solution prior to the extraction stage. It was found that nickel and cobalt extractions by LIX 84-ICNS are endothermic processes with enthalpy changes of +171.03 and +7.64 kJ/mole, respectively. Based on constructed McCabe-Thiele Diagram, nickel extraction level of more than 99.9% can be obtained in 2 stages at O/A ratio of 0.5. The highest stripping percentages of nickel and cobalt of 98.82% and 3.16%, respectively were obtained at 200 g/l H 2 SO 4 as stripping agent.
